Bangladesh Agron. J. 2024, 27(2): 61-69 

EFFECTS OF NITROGEN AND DIFFERENT RATES OF 

PENDIMETHALIN WITH BISPYRIBAC-SODIUM ON DIRECT-

SEEDED AUS RICE 
 

S. Sultana1, A.K.M.R. Amin 1, T.A. Sourav 1, M.R.H. Khan1, A.B.M.J. Islam 2, S.M. 

Masum1* 

 
1Department of Agronomy, Sher-e-Bangla Agricultural University, Sher-e-Bangla Nagar, Dhaka-1207, 

Bangladesh 
2Rice Farming Division, Bangladesh Rice Research Institute, Gazipur, Bangladesh 

*Corresponding author, Email: smmasum607@sau.edu.bd 
 

(Received: 26 April 2025, Accepted: 21 July 2025) 

 

Keywords: Dry direct-seeded rice (DSR), nitrogen rates, herbicide application, tiller number, 
dry weight, biological yield, harvest index 

 

Abstract 
 

The study was conducted at Sher-e-Bangla Agricultural University in Bangladesh, aiming to 
investigate the effects of nitrogen rates and herbicides on the competitiveness and yield 
parameters of dry direct-seeded rice (DSR) from March to July 2022. There were two factors 
in the experiment: nitrogen rates of 60 kg ha−1 (N60) and 80 kg ha−1 (N80), and the 

application of pre-emergent herbicide pendimethalin followed by post-emergent herbicide 
bispyribac-sodium. The herbicide treatments included: no weeding (H0), pendimethalin at 
1000 g a.i. ha−1 (H1), bispyribac-sodium at 25 g a.i ha⁻1 (H2), pendimethalin at 500 g a.i. 
ha−1 combined with bispyribac-sodium at 15 g a.i. ha⁻1 (H3), pendimethalin at 1000 g a.i. 
combined with bispyribac-sodium at 30 g a.i. ha−1 (H4), and pendimethalin at 1500 g a.i. 
ha−1 combined with bispyribac-sodium at 45 g a.i. ha−1 (H5). The split-plot design consisted 
of 12 treatment combinations and 3 replications, with main plots for nitrogen rates and sub-
plots for herbicidal treatments using rice var. BRRI dhan98. The result showed that the 
highest tiller number hill−1 was recorded for 80 kg ha−1 combined with pendimethalin 1000 g 
a.i. ha−1 + bispyribac-sodium 30 g a.i. ha−1 at 30, 45, 60, and 75 DAS, respectively. The 
study also exhibits the impact of nitrogen rates and herbicides on the dry weight of plants in 
BRRI dhan98 under the DSR system. Nitrogen rates did not significantly affect the dry 
weights of plants at 15, 30, and 45 days after sowing (DAS). However, the nitrogen rate of 
80 kg N ha−1 resulted in the highest dry weight at 60 and 75 DAS. The study also found that 
the biological yield and harvest index of var. BRRI dhan98 were better (9.41 and 47.74, 
respectively) in 80 kg ha−1 combined with pendimethalin 1000 g a.i. ha−1 + bispyribac-
sodium 30 g a.i. ha−1. 

 

Introduction 
 

Direct-seeded cultivation involves sowing the rice seeds directly in the field without the 
urgency of a nursery or transplanting operations (Bista, 2018). Though weed management 
remains a threat, direct-seeded rice (DSR) is achieving popularity in Asia as it is a climate-smart 

and resource-efficient production method (Ahmed et al., 2020). Direct-seeded rice is a 
promising alternative to traditional transplanting systems. The usual method is water, labor, and 
energy intensive. On the contrary, DSR enhances planting efficiency and soil health, and 
reduces methane emissions along with retrenching the labor requirement by 11-66% compared 

to pre-germinated rice (Rashid et al., 2009; Kumar and Ladha, 2011).  
In comparison with the puddled transplanted rice (PTR) system, weeds compete more 

intensively in the DSR system for resources with the crop seedlings starting from the 
germination stage (Chauhan and Johnson, 2011; Chauhan and Opeña, 2012). A 70-80% 



62                                                                                                                            Sultana et al. 

grain yield of Aus rice could be significantly hampered in the case of an improper weed 
management system (BRRI, 2008). Among the weeding methods, manual weeding is widely 
used in Bangladesh. Again, the farmers mix either pre-emergence (PRE) or post-emergence 
(POST) herbicides with water for easy application. However, this method may not be enough to 
control the vast weed species in DSR fields (Chauhan and Opeña, 2012). Seba (2022) also 
found that the application of the pre herbicide pendimethalin, succeeded by the post herbicide 
bispyribac-sodium, effectively mitigates weed proliferation and checks the emergence of 
resistant weed biotypes in the DSR system. The impacts of herbicides in DSR fields can 
fluctuate based on the N fertility levels present in the soil. Elevated nitrogen applications can 
alter the biochemical properties of both the soil and the plants, potentially augmenting or 
diminishing the absorption and efficacy of specific herbicides (Brochado et al., 2023). The study 
aims to compare N and herbicide requirements in DSR and evaluate the efficacy of pre-
emergence pendimethalin followed by post-emergence bispyribac-sodium combinations. 

 

Materials and Methods 
 

The field experiment studied the combined effects of nitrogen and pendimethalin, along 
with varying rates of bispyribac-sodium, on the growth and yield of Aus rice under dry direct-
seeded conditions at Sher-e-Bangla Agricultural University, Dhaka-1207, Bangladesh, from 
March to July 2022. The experimental field was located in AEZ-28 (The Modhupur Tract), with 
a pH range of 5.8 to 6.5. The soil was classified as silty clay, and rainfall during the growing 

period varied from 17 mm to 390.7 mm. Aus rice var. BRRI dhan98 was used as the 
experimental crop. There were two factors in the experiment: nitrogen rates of 60 kg ha−1 (N60) 
and 80 kg ha−1 (N80), and the application of pre-emergent herbicide pendimethalin followed by 
post-emergent herbicide bispyribac-sodium. The herbicide treatments included: no weeding (H0), 
pendimethalin at 1000 g a.i. ha−1 (H1), bispyribac-sodium at 25 g a.i. ha−1 (H2), pendimethalin 
at 500 g a.i. ha−1 combined with bispyribac-sodium at 15 g a.i. ha−1 (H3), pendimethalin at 
1000 g a.i. ha−1 combined with bispyribac-sodium at 30 g a.i. ha−1 (H4), and pendimethalin at 
1500 g a.i. ha−1 combined with bispyribac-sodium at 45 g a.i. ha−1 (H5). The study employed a 
split-plot design with 12 treatment combinations, each replicated three times. The main plots 
varied in nitrogen levels, while the sub-plots incorporated different rates of pendimethalin and 
bispyribac-sodium. On March 21, 2022, the field was cultivated with a power tiller and irrigated 
after three ploughs and cross-ploughs. Weeds and pests were cleared. By March 27, the final 
layout was completed; each plot was leveled with a wooden board. Nutrients, including 
phosphorus (P), potassium (K), sulfur (S), and zinc (Zn), were applied to rice per BRRI’s Aus rice 
recommendations. Fertilizer doses included: triple superphosphate (90 kg ha−1), muriate of 
potash (40 kg ha−1), gypsum (60 kg ha−1), and zinc sulfate (10 kg ha−1). All fertilizers, except 
urea, were applied during land preparation, with urea split into three applications: first at 
preparation, then at 25 days and 50 days after sowing, based on treatments. The field was 
irrigated only at the flowering stage of the tested crop. The data were analyzed and mean 
differences were assessed by using the least significant difference (LSD) test at a 5% significance 
level. 

 

Results and Discussion 
 

Total number of tillers hill−1 

The total number of tillers hill−1 did not significantly differ across different nitrogen rates 
except at 75 days after sowing (DAS) (Table 1). The highest (9) number of total tillers hill−1 at 75 
DAS was found with the N80 treatment, while the lowest (8) from the N60 treatment. The total 
number of tillers hill−1 of direct-seeded Aus rice varied significantly as a result of the herbicides 
used (Table 1). Experimental results revealed that, at 15 DAS, the maximum tiller number hill−1 
(5) was recorded from the combined pre-emergence herbicide pendimethalin 1000 g a.i. ha−1 + 



Effects of nitrogen and pendimethalin with bispyribac-sodium on direct-seeded aus rice                             63 

post-emergence bispyribac-sodium 30 g a.i. ha−1. At 30 DAS, the maximum tiller number hill−1 
(9) from mixed herbicide pendimethalin 1000 g a.i. ha−1 + bispyribac-sodium 30 g a.i. ha−1. At 
45 DAS, the highest tiller number hill−1 (13) was recorded from the pendimethalin 1000 g a.i. 
ha−1 + bispyribac-sodium 30 g a.i. ha−1 (H4). At 60 DAS, the maximum tiller number in hill−1 
(13) was recorded for pendimethalin 1000 g a.i. ha−1 + bispyribac-sodium 30 g a.i. ha−1 (H4). 
The combined impact of pendimethalin 1000 g a.i. ha−1 + bispyribac-sodium 30 g a.i. ha−1 (H4) 
resulted in the highest tiller number hill−1 in both nitrogen doses (Table 1). The tiller number 
hill−1 for N80 combined with H4 is 5, 9, 13, and 13 at 30, 45, 60, and 75 DAS, respectively. 
The combined effect of pendimethalin 1500 g a.i. ha−1 + bispyribac-sodium 45 g a.i. ha−1 (H5) 
was also similar at 30, 45, 60, and 75 DAS, respectively, for N80H5. On the other hand, N60H0 
resulted in the lowest tillers number hill−1. 
 
Table 1. Effect of nitrogen rates and pre and post-emergence herbicides rates on tiller number hill−1 of var. 

BRRI dhan98 under DSR system 
 

Here: N60=60 kg N ha−1 and N80=80 kg N ha−1; H0= No weeding, H1= pendimethalin 1000 g a.i. ha−1 + bispyribac-
sodium 0 g a.i. ha−1; H2= pendimethalin 0 g a.i. ha−1 + bispyribac-sodium 25 g a.i. ha−1; H3= pendimethalin 500 g a.i. 
ha−1 + bispyribac-sodium 15 g a.i. ha−1; H4= pendimethalin 1000 g a.i. ha−1 + bispyribac-sodium 30 g a.i. ha−1; H5= 
pendimethalin 1500 g a.i. ha−1 + bispyribac-sodium 45 g a.i. ha−1 

Treatments 
Number of tillers 

30 DAS 45 DAS 60 DAS 75 DAS 

Nitrogen levels 

N60 3.83 6.38 8.89 8.00 b 

N80 3.61 6.61 9.22 9.22 a 

LSD (0.05) NS NS NS 0.48 

CV (%) 8.96 15.60 3.19 3.87 

Pendimethalin fb. Bispyribac-sodium rates 

H0 3.50 bc 4.67 d 6.83 d 4.17 e 

H1 3.67 b 6.17 c 8.83 c 8.83 c 

H2 3.00 c 4.67 d 6.17 d 6.17 d 

H3 3.83 b 7.83 b 9.83 b 9.83 b 

H4 4.67 a 9.00 a 12.83 a 12.83 a 

H5 3.67 b 6.67 c 9.83 b 9.83 b 

LSD (0.05) 0.55 0.77 0.68 0.67 

CV (%) 12.34 9.80 6.27 6.48 

Nitrogen levels × Pendimethalin fb. Bispyribac-sodium rates 

N60H0 3.67 bc 4.33 f 5.33 g 0.00 h 

N60H1 4.00 ab 5.33 ef 9.00 de 9.00 de 

N60H2 3.00 c 5.00 ef 6.67 f 6.67 f 

N60H3 4.00 ab 7.67 bc 9.33 d 9.33 d 

N60H4 4.67 a 8.67 ab 12.33 b 12.33 b 

N60H5 3.67 bc 7.33 cd 10.67 c 10.67 c 

N80H0 3.33 bc 5.00 ef 8.33 e 8.33 e 

N80H1 3.33 bc 7.00 cd 8.67 de 8.67 de 

N80H2 3.00 c 4.33 f 5.67 g 5.67 g 

N80H3 3.67 bc 8.00 bc 10.33 c 10.33 c 

N80H4 4.67 a 9.33 a 13.33 a 13.33 a 

N80H5 3.67 bc 6.00 de 9.00 de 9.00 de 

LSD (0.05) 0.83 1.65 0.95 0.96 

CV (%) 12.34 9.80 6.27 6.48 



64                                                                                                                            Sultana et al. 

Dry weight of plants 

Though nitrogen rates didn’t play a role in causing significant differences in dry weights 
of plants at 15, 30, and 45 DAS but 80 kg N ha−1 resulted in the highest dry weight at 60 and 
75 DAS (Table 2).  

 
Table 2. Effect of nitrogen rates and pre and post-emergence herbicide rates on the dry weight of plants of 

var.  BRRIdhan98 under the DSR system 
 

Treatments 
Dry Weight (g plant−1) 

15 DAS 30 DAS 45 DAS 60 DAS 75 DAS 

Nitrogen levels 

N60 2.42 5.58 12.95 29.21 b 31.21 b 

N80 2.53 5.00 14.08 35.19 a 37.03 a 

LSD (0.05) NS NS NS 1.12 0.97 
CV (%) 11.17 15.85 6.09 2.43 1.99 

Pendimethalin fb. Bispyribac-sodium rates 

H0 1.85 c 4.60 d 9.54 d 14.75 e 11.52 e 

H1 1.71 c 5.96 ab 13.95 b 29.97 c 36.04 c 

H2 2.84 b 5.42 bc 13.70 b 27.01 d 27.48 d 

H3 1.87 c 4.15 d 12.39 c 39.44 b 40.92 b 

H4 3.70 a 6.40 a 15.64 a 42.23 a 44.90 a 

H5 2.88 b 5.22 c 15.88 a 39.81 b 43.85 a 

LSD (0.05) 0.41 0.57 1.43 1.49 1.45 
CV (%) 13.79 9.01 4.60 3.83 3.52 

Nitrogen levels × Pendimethalin fb. Bispyribac-sodium rates 

N60H0 1.19 fg 4.42 de 7.60 g 8.30 j 0.00 g 

N60H1 2.53 b-d 6.60 ab 13.32 cd 26.06 h 38.26 c 

N60H2 2.78 bc 6.27 ab 13.82 cd 25.72 h 26.54 e 

N60H3 1.71 ef 4.29 de 11.84 ef 38.32 de 40.97 b 

N60H4 3.69 a 6.80 a 15.13 ab 39.76 cd 41.24 b 

N60H5 2.61 b-d 5.09 c-e 16.01 ab 37.11 e 40.24 bc 

N80H0 2.51 cd 4.77 de 11.47 f 21.19 i 23.04 f 

N80H1 0.89 g 5.32 b-d 14.59 bc 33.88 f 33.83 d 

N80H2 2.91 bc 4.56 de 13.58 cd 28.31 g 28.42 e 

N80H3 2.02 de 4.02 e 12.93 de 40.56 bc 40.87 b 

N80H4 3.71 a 6.00 a-c 16.16 a 44.69 a 48.55 a 

N80H5 3.15 ab 5.36 b-d 15.75 ab 42.52 b 47.46 a 

LSD (0.05) 0.63 1.33 1.43 2.15 2.05 
CV (%) 13.79 9.01 4.60 3.83 3.52 

Here: N60=60 kg N ha−1 and N80=80 kg N ha−1; H0= No weeding, H1= pendimethalin 1000 g a.i. ha−1 + bispyribac-
sodium 0 g a.i. ha−1; H2= pendimethalin 0 g a.i. ha−1 + bispyribac-sodium 25 g a.i. ha−1; H3= pendimethalin 500 g a.i. 
ha−1 + bispyribac-sodium 15 g a.i. ha−1; H4= pendimethalin 1000 g a.i. ha−1 + bispyribac-sodium 30 g a.i. ha−1; H5= 
pendimethalin 1500 g a.i. ha−1 + bispyribac-sodium 45 g a.i. ha−1 

 
Dry weight of plants significantly differed due to the effect of herbicides (Table 2). At 15 

DAS, the maximum dry weight (g) (3.70) was recorded from the combined pre-emergence 



Effects of nitrogen and pendimethalin with bispyribac-sodium on direct-seeded aus rice                             65 

herbicide pendimethalin 1000 g a.i. ha−1 + post-emergence bispyribac-sodium 30 g ai ha−1 (H4). 
At 30 DAS, a similar trend was followed. At 45 DAS, the highest dry weight (g) (15.88) was 
recorded from the pendimethalin 1500 g a.i. ha−1 + bispyribac-Sodium 45 g a.i. ha−1 (H5). At 
60 DAS, the maximum dry weight (g) (39.81) was recorded from the pendimethalin 1000 g a.i. 
ha−1 + bispyribac-Sodium 30 g a.i. ha−1 (H4). Lodhi (2016) also found that weed control 
treatments significantly impact dry matter accumulation after sowing. Weedy check plots had 
the lowest dry matter production but increased significantly with weed control treatments at all 
growth intervals. Pendimethalin 1000 g a.i. ha−1 + bispyribac-sodium 30 g a.i. ha−1 (H4) resulted 
in the dry weight (g) in both nitrogen doses (Table 2).  Dry weight (g) for N80H4 was 3.71, 6.00, 
16.16, 44.69, and 48.55 at 15, 30, 45, 60, and 75 DAS, respectively. The effect of 80 kg N 
ha−1 and pendimethalin 1500 g a.i. ha−1 + bispyribac-sodium 45 g a.i. ha−1 (H5) was also 
satisfactory for N80H5. On the other hand, N60H0 resulted in the lowest dry weight (g). 
 

No. of panicles m−2 

The number of panicles m−2 was significantly affected by nitrogen rates. The maximum 
number of panicles m−2 was recorded with 80 kg N ha−1, compared with 60 kg N ha−1 was 151 
m−2 (Table 3). Panicle number (250 m−2) was higher in the herbicide-treated plots than in the 
weedy check plots and was the highest in the highest dose of pre-post emergence herbicide, 
i.e., pendimethalin 1500 g a.i. ha−1 + bispyribac-sodium 45 g a.i. ha−1 (H5) (Table 3). On the 
other hand, the lowest number of panicles was observed at the plots from the control (0 m−2). 
Similar results were also noted by Hossain (2015). The combined effect, pendimethalin 1500 g 
a.i. ha−1 + bispyribac-sodium 45 g a.i. ha−1 (H5) resulted in the highest number of panicles m−2 
(255 m−2) at the nitrogen dose of 60 kg N ha−1 (Table 3). On the other hand, N60H0 resulted in 
the lowest no. of panicles m−2 (0 m−2). 

 

Panicle length (cm) 

The panicle length (cm) was significantly affected by nitrogen rates. The highest panicle 
length (14.87 cm) was recorded for the plots treated with 80 kg N ha−1, (Table 3). The panicle 
length (19.55 cm) was higher in the herbicide-treated plots than in the weedy check plots and 
gave the highest, followed by pre-post emergence herbicide, i.e., pendimethalin 1000 g a.i. 
ha−1 + bispyribac-sodium 30 g a.i. ha−1 (H4) (Table 3). On the other hand, the lowest panicle 

length (cm) was observed at the control plot. According to research by Jabran et al., (2012), 
using herbicides to suppress weeds produces longer panicles than the weedy check (control). 
Pendimethalin 1000 g a.i. ha−1 + bispyribac-sodium 30 g a.i. ha−1 (H4) resulted in the maximum 
panicle length (20.56 cm) at 80 kg N ha−1 (Table 3), followed by N80H5 with 80 kg N ha−1, and 
the herbicide dose was pendimethalin 1500 g a.i. ha−1 + bispyribac-Sodium 45 g a.i. ha−1 
(19.59 cm). On the other hand, N60H0 resulted in the lowest no. of panicles m−2 (0 cm).  

 

Number of filled grains panicle−1 

The highest number of filled grain panicle−1 (37) was recorded for the plots treated with 

80 kg N ha−1 (Table 3). Yesuf and Balcha (2014), Chamely et al., (2015), and Zhang et al., 
(2020) have documented that the application of nitrogen fertilizer has a notable impact on rice 
grains, specifically length and width. Pendimethalin 1500 g a.i. ha−1 + bispyribac-sodium 45 g 
a.i. ha−1 treated plots had more filled grain panicle−1 than the other combinations (Table 3). On 
the other hand, the lowest number of filled grain panicle−1 was observed from the control plots 
(0). N80H5 resulted in the most filled grain panicle−1 (72), at the nitrogen dose of 80 kg N ha−1, 
while N60H0 resulted in the lowest number of filled grain panicle−1 (0). 
 

1000-grain weight 

The 1000-grain weight (g) was significantly affected by nitrogen rates. The highest 
number of 1000-grain weight (17.89 g) was recorded from 80 kg N ha−1 pendimethalin 1500 g 
a.i. ha−1 + bispyribac-sodium 45 g a.i. ha−1 treated plots, which had more 1000-grain weight 



66                                                                                                                            Sultana et al. 

than the other combinations (Table 3). The 1000-grain weight (g) was higher in the herbicide-
treated plots than in the weedy check plots and gave the highest (23.67 g) from treatment H5. 
The result of pendimethalin 1000 g a.i. ha−1 + bispyribac-sodium 30 g a.i. ha−1 (H4) was also 
similar to H5 (22.33 g).  

 
Table 3. Effect of nitrogen rates and pre and post-emergence herbicides rates on yield contributing 

parameters of var. BRRI dhan98 under DSR system 
 

Treatments 
Panicle m−2 

(No.) 
Panicle length 

(cm) 
Filled grains 

panicle−1 (No.) 
1000-grain 
weight (g) 

Nitrogen levels 

N60 151 b 12.23 29.83 b 13.94 b 

N80 156 a 14.87 36.78 a 17.89 a 

LSD (0.05) 2.48 1.58 3.52 0.86 

CV (%) 20.76 15.83 7.37 3.78 

Pendimethalin fb. Bispyribac-sodium rates 

H0 0.00 d 0.00 d 0.00 e 0.00 d 

H1 210.00 b 16.29 b 29.33 c 19.50 b 

H2 42.00 c 7.00 c 9.50 d 9.17 c 

H3 206.40 b 19.11 a 26.33 c 20.83 b 

H4 212.40 ab 19.55 a 63.67 b 22.33 a 

H5 250.20 a 19.36 a 71.00 a 23.67 a 

LSD (0.05) 38.77 1.40 4.53 1.39 

CV (%) 20.97 8.56 11.29 7.22 

Nitrogen levels × Pendimethalin fb. Bispyribac-sodium rates 

N60H0 0.00 e 0.00 e 0.00 g 0.00 g 

N60H1 200.40 bc 16.99 b-d 26.33 e 20.33 de 

N60H2 0.00 e 0.00 e 0.00 g 0.00 g 

N60H3 211.20 a-c 18.72 a-c 19.67 f 19.33 d-f 

N60H4 238.80 a-c 18.55 a-c 63.00 c 21.00 cd 

N60H5 255.60 a 19.13 ab 70.00 ab 23.00 ab 

N80H0 0.00 e 0.00 e 0.00 g 0.00 g 

N80H1 219.60 a-c 15.59 cd 32.33 de 18.67 ef 

N80H2 84.00 d 14.00 d 19.00 f 18.33 f 

N80H3 201.60 a-c 19.50 ab 33.00 d 22.33 bc 

N80H4 186.00 c 20.56 a 64.33 bc 23.67 ab 

N80H5 244.80 ab 19.59 ab 72.00 a 24.33 a 

LSD (0.05) 64.27 1.98 6.60 1.94 

CV (%) 20.97 8.56 11.29 7.22 
Here: N60=60 kg N ha−1 and N80=80 kg N ha−1; H0= No weeding, H1= pendimethalin 1000 g a.i. ha−1 + bispyribac-
sodium 0 g a.i. ha−1; H2= pendimethalin 0 g a.i. ha−1 + bispyribac-sodium 25 g a.i. ha−1; H3= pendimethalin 500 g a.i. 
ha−1 + bispyribac-sodium 15 g a.i. ha−1; H4= pendimethalin 1000 g a.i. ha−1 + bispyribac-sodium 30 g a.i. ha−1; H5= 
pendimethalin 1500 g a.i. ha−1 + bispyribac-sodium 45 g a.i. ha−1 



Effects of nitrogen and pendimethalin with bispyribac-sodium on direct-seeded aus rice                             67 

On the other hand, the lowest number of panicles was observed from the control plot 

(0 g). Similar findings were reported by Jabran et al., (2012).  Pendimethalin 1500 g a.i. ha−1 + 
bispyribac-sodium 45 g a.i. ha−1 (H5) resulted in the highest 1000-grain weight (g) at 80 kg N 
ha−1 (Table 3). Treatment N80H5 resulted in the highest 1000-grain weight (24.33 g), followed 
by N80H4 80 kg N ha−1, and the herbicide dose was pendimethalin 1000 g a.i. ha−1 + 
bispyribac-sodium 30 g a.i. ha−1 (23.67 g). On the contrary, N60H0 resulted in the lowest 1000-
grain weight (0 g). 

 

Biological yield 

The biological yield was considerably different for nitrogen doses (Fig. 1). The highest 
biological yield (4.60 t ha−1) was recorded with 80 kg N ha−1.  
 

  
 

Fig. 1. Effect of nitrogen rates and pre and post-emergence herbicide doses on biological yield. Here: 
N60=60 kg N ha−1 and N80=80 kg N ha−1; H0= No weeding, H1= pendimethalin 1000 g a.i. ha−1 
+ bispyribac-sodium 0 g a.i. ha−1; H2= pendimethalin 0 g a.i. ha−1 + bispyribac-sodium 25 g a.i. 
ha−1; H3= pendimethalin 500 g a.i. ha−1 + bispyribac-sodium 15 g a.i. ha−1; H4= pendimethalin 
1000 g a.i. ha−1 + bispyribac-sodium 30 g a.i. ha−1; H5= pendimethalin 1500 g a.i. ha−1 + 
bispyribac-sodium 45 g a.i. ha−1. 

 
The biological yield significantly differed due to the herbicide application, where 

pendimethalin 1000 g a.i. ha−1 + bispyribac-sodium 30 g a.i. ha−1 treated plots had more 
biological yield (t ha−1) than the other combinations (Fig. 2).  

 

  
 

Fig. 2. Effect of nitrogen rates and pre and post-emergence herbicide doses on harvest index (%). Here: 
N60=60 kg N ha−1 and N80=80 kg N ha−1; H0= No weeding, H1= pendimethalin 1000 g a.i. ha−1 + 
bispyribac-sodium 0 g a.i. ha−1; H2= pendimethalin 0 g a.i. ha−1 + bispyribac-sodium 25 g a.i. ha−1; 
H3= pendimethalin 500 g a.i. ha−1 + bispyribac-sodium 15 g a.i. ha−1; H4= pendimethalin 1000 g 
a.i. ha−1 + bispyribac-sodium 30 g a.i. ha−1; H5= pendimethalin 1500 g a.i. ha−1 + bispyribac-
sodium 45 g a.i. ha−1 

 
The biological yield (8.94 t ha−1) was higher in the herbicide-treated plots than in the 

weedy check plots. On the other hand, the lowest biological yield (t ha−1) was where weeding 

was not performed (0 t ha−1). Hasanuzzaman et al., (2008) corroborate the findings that the 



68                                                                                                                            Sultana et al. 

efficacy of the herbicidal interventions impacted the biological yield. Pendimethalin 1000 g ai 
ha−1 + bispyribac-sodium 30 g a.i. ha−1 (H4) resulted in the highest biological yield of 80 kg N 
ha−1 (Table 4). Treatment N80H4 resulted in the highest biological yield (9.41 t ha−1) where 
N60H0 resulted in the lowest biological yield (0 t ha−1). 

 

Harvest Index 

The harvest index (%) was considerably different for nitrogen doses (Fig. 2). The highest 
harvest index (31.06%) was recorded with 80 kg N ha−1. The harvest index (%) significantly 
differed due to the herbicide application. Pendimethalin 1000 g a.i. ha−1 + bispyribac-sodium 
30 g a.i. ha−1 treated plots had more harvest index (%) than the other combinations (Table 4 
and Fig. 3). The harvest index (45.76%) was higher in the herbicide-treated plots than in the 
weedy check plots, followed by (H4). On the other hand, the lowest harvest index (%) was 
observed where weeding was not performed (0%). Pendimethalin 1000 g a.i. ha−1 + bispyribac-
sodium 30 g a.i. ha−1 (H4) resulted in the highest harvest index (47.74%). at 80 kg N ha−1 (Table 
4). On the other hand, N60H0 resulted lowest harvest index (0%). 

 
Table 4. Effect of nitrogen rates and pre and post-emergence herbicide rates on the yield of var.  BRRI 

dhan98 under the DSR system 
 

Treatments Biological yield (t ha−1) Harvest index(%) 

N60H0 0.00 f 0.00 g 

N60H1 2.32 e 39.28 c 

N60H2 0.0 f 0.00 g 

N60H3 2.10 e 28.21 e 

N60H4 8.48 c 43.77 b 

N60H5 8.26 c 42.39 b 

N80H0 0.00 f 0.00 g 

N80H1 3.27 d 35.59 d 

N80H2 2.42 e 24.60 f 

N80H3 3.52 d 33.86 d 

N80H4 9.41 a 47.74 a 

N80H5 8.94 b 44.57 ab 

LSD (0.05) 0.43 3.43 

CV (%) 6.02 6.30 

Here: N60=60 kg N ha−1 and N80=80 kg N ha−1; H0= No weeding, H1= pendimethalin 1000 g a.i. ha−1 + bispyribac-
sodium 0 g a.i. ha−1; H2= pendimethalin 0 g a.i. ha−1 + bispyribac-sodium 25 g a.i. ha−1; H3= pendimethalin 500 g a.i. 
ha−1 + bispyribac-sodium 15 g a.i. ha−1; H4= pendimethalin 1000 g a.i. ha−1 + bispyribac-sodium 30 g a.i. ha−1; H5= 
pendimethalin 1500 g a.i. ha−1 + bispyribac-sodium 45 g a.i. ha−1 

 

Conclusion 
 

The findings of this study showed that overall growth and crop production properties 
were significantly enhanced with fertilizer application of 80 kg N ha⁻1.Moreover, weed control 
was found effective when pendimethalin @ 1500 g a.i. ha−1 in combination with bispyribac-
sodium @ 45 g a.i. ha⁻1 was applied. These findings have also resulted in an enhanced yield of 

DSR, as well as being effectively employed for weed management in direct-seeded Aus rice of 
var. BRRI dhan98. 
 

 

 



Effects of nitrogen and pendimethalin with bispyribac-sodium on direct-seeded aus rice                             69 

Acknowledgment 
 

` The authors gratefully acknowledge the financial support of the SAURES, Sher-e-
Bangla Agricultural University, Bangladesh, to conduct this research. 
 

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